Abstract

Nanosuspensions have widely attracted attention as (topical) delivery systems for pharmaceutical active ingredients, but they are also relevant to the cosmetics industry. The purpose of this study is to optimize a carrier system for inorganic sunscreens in order to qualify for natural cosmetics. Beeswax-jojoba oil nanosuspensions with titanium dioxide as inorganic sunscreen were manufactured by using high-pressure homogenization. The sunscreen-loaded wax nanoparticles were analyzed by particle size measurements (PIDS technique), sun protection factor (SPF) analyses and visualization methods such as transmission (TEM) and scanning electron microscopy (SEM), respectively. The nanosuspensions showed high SPFs around 80 along with particle sizes around 600 nm. SEM and TEM revealed close contact between beeswax and titanium dioxide crystals. Part of the titanium dioxide was not incorporated but was deposited at the surface of the particles.

INTRODUCTION
Organic and natural ingredients have become a major trend in cosmetics in recent years. According to German Industrial Association (1), every eighth Euro spent on cosmetics in drug stores is spent on natural cosmetics. A huge and still growing variety of such products ranges from care to decorative cosmetics and is offering gentle, wholesome care helping to maintain and beautify the human skin. Using only organic and/or natural raw materials, these products are highly regarded by those consumers who are looking for ingredients being friendly to both skin and environment.
Being a part of care cosmetics, sunscreens play an important role in photo protection and thus skin cancer prevention. The growing awareness of the harmful effects of sunrays indicates how important the use of sunscreen formulations is (2-3). As a consequence of an increasing sun exposure, the incidence of skin cancer and other disorders has surged over recent years, which implicates an increasing interest in sunscreen products to achieve an adequate protection against both UV-A and UV-B radiation (4). Active ingredients of sunscreens are subdivided into inorganic an ...